Within- and trans-generational plasticity: seed germination responses to light quantity and quality.

Katherine Vayda,Kathleen Donohue,Gabriela Alejandra Auge

doi:10.1093/aobpla/ply023

Abstract

Plants respond not only to the environment in which they find themselves, but also to that of their parents. The combination of within- and trans-generational phenotypic plasticity regulates plant development. Plants use light as source of energy and also as a cue of competitive conditions, since the quality of light (ratio of red to far-red light, R:FR) indicates the presence of neighbouring plants. Light regulates many aspects of plant development, including seed germination. To understand how seeds integrate environmental cues experienced at different times, we quantified germination responses to changes in light quantity (irradiance) and quality (R:FR) experienced during seed maturation and seed imbibition in Arabidopsis thaliana genotypes that differ in their innate dormancy levels and after treatments that break or reinduce dormancy. In two of the genotypes tested, reduced irradiance as well as reduced R:FR during seed maturation induced higher germination; thus, the responses to light quantity and R:FR reinforced each other. In contrast, in a third genotype, reduced irradiance during seed maturation induced progeny germination, but response to reduced R:FR was in the opposite direction, leading to a very weak or no overall effect of a simulated canopy experienced by the mother plant. During seed imbibition, reduced irradiance and reduced R:FR caused lower germination in all genotypes. Therefore, responses to light experienced at different times (maturation vs. imbibition) can have opposite effects. In summary, seeds responded both to light resources (irradiance) and to cues of competition (R:FR), and trans-generational plasticity to light frequently opposed and was stronger than within-generation plasticity.

Highlights

Plants respond to the environmental conditions in which they find themselves, and to those of their parents (Schlichting 1986; Kirkpatrick and Lande 1989; Sultan 2000; Galloway and Etterson 2007; Snell-Rood 2013; reviewed in Auge et al 2017b)
Genotypes differed significantly in their germination responses to light experienced during seed maturation and seed imbibition, differences with Col could be confounded with batch
The observation that genetic differences in dormancy influence germination responses to light suggests that natural genetic variation in the ability to respond to light cues may in part be caused by genetic variation in innate dormancy, affecting in turn how maternal effects are expressed in the generation. Germination responds both to changes in light irradiance and R:FR, and the combination of these responses determines the response to vegetation canopy

Summary

Introduction

Plants respond to the environmental conditions in which they find themselves (within-generational plasticity), and to those of their parents (trans-generational plasticity) (Schlichting 1986; Kirkpatrick and Lande 1989; Sultan 2000; Galloway and Etterson 2007; Snell-Rood 2013; reviewed in Auge et al 2017b). When dispersal is limited and environments are stable over time, parental environments may be accurate predictors of progeny environments, such that trans-generational plasticity can induce progeny phenotypes that are suited to their environments (Galloway and Etterson 2007; Holeski et al 2012; Latzel et al 2014; Dey et al 2016; Herman and Sultan 2016; Singh et al 2017). Germination is highly environmentally cued, and it responds to environmental conditions experienced both by maternal parents and by seeds themselves (Gutterman 2000; Donohue 2009; Graeber et al 2012). Some environmental factors experienced in parental generations can alter how seeds respond to their own environments (reviewed in Auge et al 2017b)

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